There is overwhelming evidence that children's first words are primarily nouns even across languages. These data are interpreted as evidence of a "Natural Partitions Theory," one that holds that the concepts referred to by nouns are conceptually more basic than those referred to by verbs or prepositions. Analysis of data from cross-linguistic studies designed to eliminate nonconceptual differences between words in a language that might account for the earlier acquisition of nouns--such as the position of a word in the sentence, morphological transparency (the ease with which the root can be heard in various uses of the word), and patterns of language teaching strategies--leaves some version of the Natural Partitions hypothesis as the most reasonable view of early vocabulary acquisition. A cross-linguistic examination of a single sentence suggests that if objecthood is created by spatial relations among perceptual elements, then good concrete objects are particularly cohesive collections of percepts. These highly cohesive collections of perceptual information tend to be lexicalized as nouns by almost every language. Object concepts are given to language users by the world and can be learned one at a time, while predicate concepts form a system in each language, that, from a child's point of view, must be discovered. (HTH)